Key idea. Make each opponent-move-and-reply remove four stones.

1. The first player takes 2 stones from 30, leaving 28, a multiple of 4.

2. Then use these replies: if the opponent takes 1, take 3; if the opponent takes 2, take 2; if the opponent takes 3, take 1.

3. After each completed pair of moves, the remaining pile is a smaller multiple of 4: 24, 20, 16, 12, 8, 4, then 0.

4. Every reply is allowed and enough stones remain for it. From 4 stones, whatever the opponent takes, the first player can take the rest.

5. The opponent is then left with no move, so loses.

Remember. The same strategy changes naturally when the allowed moves change from 1-2 to 1-3.